Always allow viewport zooming

The changeset that introduced this [1] didn't specify an Opera Mobile
browser version

Tried against latest Opera Mobile and it is fine so let's throw away

[1] I9e3e387cc3454e05156c2e285982eae36cbb85c7

Change-Id: Ia3877bb4cb3c6abc8536b92538c54c33a18e6d9e